In recent years, adhesive tapes have come to be employed in a wide range of applications, e.g., for production and construction of electronic parts and automotive parts. In these applications, the adhesive tapes are often subjected to higher stresses and higher temperatures during use and, therefore, required to be highly cohesive and heat-resistant. Particularly, adhesive tapes to be used in production processes for electronic parts, semiconductor devices and flat display devices such as LCDs and PDPs are generally subjected to temperatures of 100° C. or higher and, therefore, required to have sufficient adhesiveness and cohesiveness at higher temperatures.
However, prior-art adhesive compositions are disadvantageously poorer in heat resistance and cohesiveness at higher temperatures. One approach to this problem is to blend various types of inorganic fillers to an adhesive agent for improvement of the cohesiveness and the heat resistance. Particularly, it is reported that, where a lipophilic layered clay mineral (hereinafter referred to simply as “layered clay mineral”) is dispersed as the inorganic filler in the adhesive agent, the heat resistance and the cohesiveness are both improved (see Patent Documents 1 and 2).    Patent Document 1: JP-A-2005-344008    Patent Document 2: JP-A-2005-154581
However, even if an organophilic layered clay mineral prepared by organically modifying a layered clay mineral (e.g., a smectite such as montmorillonite, beidellite, nontronite, saponite, hectorite or stevensite, or a mica such as muscovite, phlogopite, taeniolite, biotite, margarite, clintonite or tetrasilisic mica) with an alkyl ammonium salt is dispersed in the adhesive agent, the organophilic layered clay mineral does not undergo complete interlayer separation, but is present in an adhesive agent layer with its layers being in a stacked state. This results in variations in adhesiveness at higher temperatures.